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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.xml.transform;

import java.util.Properties;

/**
 * An instance of this abstract class can transform a
 * source tree into a result tree.
 *
 * <p>An instance of this class can be obtained with the
 * {@link TransformerFactory#newTransformer TransformerFactory.newTransformer}
 * method. This instance may then be used to process XML from a
 * variety of sources and write the transformation output to a
 * variety of sinks.</p>
 *
 * <p>An object of this class may not be used in multiple threads
 * running concurrently.  Different Transformers may be used
 * concurrently by different threads.</p>
 *
 * <p>A <code>Transformer</code> may be used multiple times.  Parameters and
 * output properties are preserved across transformations.</p>
 *
 * @author <a href="Jeff.Suttor@Sun.com">Jeff Suttor</a>
 */
public abstract class Transformer {

  /**
   * Default constructor is protected on purpose.
   */
  protected Transformer() {
  }

  /**
   * <p>Reset this <code>Transformer</code> to its original configuration.</p>
   *
   * <p><code>Transformer</code> is reset to the same state as when it was created with
   * {@link TransformerFactory#newTransformer()},
   * {@link TransformerFactory#newTransformer(Source source)} or
   * {@link Templates#newTransformer()}.
   * <code>reset()</code> is designed to allow the reuse of existing <code>Transformer</code>s
   * thus saving resources associated with the creation of new <code>Transformer</code>s.</p>
   *
   * <p>The reset <code>Transformer</code> is not guaranteed to have the same {@link URIResolver}
   * or {@link ErrorListener} <code>Object</code>s, e.g. {@link Object#equals(Object obj)}.
   * It is guaranteed to have a functionally equal <code>URIResolver</code>
   * and <code>ErrorListener</code>.</p>
   *
   * @throws UnsupportedOperationException When implementation does not override this method.
   * @since 1.5
   */
  public void reset() {

    // implementors should override this method
    throw new UnsupportedOperationException(
        "This Transformer, \"" + this.getClass().getName()
            + "\", does not support the reset functionality."
            + "  Specification \"" + this.getClass().getPackage().getSpecificationTitle() + "\""
            + " version \"" + this.getClass().getPackage().getSpecificationVersion() + "\""
    );
  }

  /**
   * <p>Transform the XML <code>Source</code> to a <code>Result</code>.
   * Specific transformation behavior is determined by the settings of the
   * <code>TransformerFactory</code> in effect when the
   * <code>Transformer</code> was instantiated and any modifications made to
   * the <code>Transformer</code> instance.</p>
   *
   * <p>An empty <code>Source</code> is represented as an empty document
   * as constructed by {@link javax.xml.parsers.DocumentBuilder#newDocument()}.
   * The result of transforming an empty <code>Source</code> depends on
   * the transformation behavior; it is not always an empty
   * <code>Result</code>.</p>
   *
   * @param xmlSource The XML input to transform.
   * @param outputTarget The <code>Result</code> of transforming the <code>xmlSource</code>.
   * @throws TransformerException If an unrecoverable error occurs during the course of the
   * transformation.
   */
  public abstract void transform(Source xmlSource, Result outputTarget)
      throws TransformerException;

  /**
   * Add a parameter for the transformation.
   *
   * <p>Pass a qualified name as a two-part string, the namespace URI
   * enclosed in curly braces ({}), followed by the local name. If the
   * name has a null URL, the String only contain the local name. An
   * application can safely check for a non-null URI by testing to see if the
   * first character of the name is a '{' character.</p>
   * <p>For example, if a URI and local name were obtained from an element
   * defined with &lt;xyz:foo
   * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
   * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
   * Note that no prefix is used.</p>
   *
   * @param name The name of the parameter, which may begin with a namespace URI in curly braces
   * ({}).
   * @param value The value object.  This can be any valid Java object. It is up to the processor to
   * provide the proper object coersion or to simply pass the object on for use in an extension.
   * @throws NullPointerException If value is null.
   */
  public abstract void setParameter(String name, Object value);

  /**
   * Get a parameter that was explicitly set with setParameter.
   *
   * <p>This method does not return a default parameter value, which
   * cannot be determined until the node context is evaluated during
   * the transformation process.
   *
   * @param name of <code>Object</code> to get
   * @return A parameter that has been set with setParameter.
   */
  public abstract Object getParameter(String name);

  /**
   * <p>Set a list of parameters.</p>
   *
   * <p>Note that the list of parameters is specified as a
   * <code>Properties</code> <code>Object</code> which limits the parameter
   * values to <code>String</code>s.  Multiple calls to
   * {@link #setParameter(String name, Object value)} should be used when the
   * desired values are non-<code>String</code> <code>Object</code>s.
   * The parameter names should conform as specified in
   * {@link #setParameter(String name, Object value)}.
   * An <code>IllegalArgumentException</code> is thrown if any names do not
   * conform.</p>
   *
   * <p>New parameters in the list are added to any existing parameters.
   * If the name of a new parameter is equal to the name of an existing
   * parameter as determined by {@link java.lang.Object#equals(Object obj)},
   *  the existing parameter is set to the new value.</p>
   *
   * @param params Parameters to set.
   *
   * @throws IllegalArgumentException If any parameter names do not conform
   *   to the naming rules.
   */

  /**
   * Clear all parameters set with setParameter.
   */
  public abstract void clearParameters();

  /**
   * Set an object that will be used to resolve URIs used in
   * document().
   *
   * <p>If the resolver argument is null, the URIResolver value will
   * be cleared and the transformer will no longer have a resolver.</p>
   *
   * @param resolver An object that implements the URIResolver interface, or null.
   */
  public abstract void setURIResolver(URIResolver resolver);

  /**
   * Get an object that will be used to resolve URIs used in
   * document().
   *
   * @return An object that implements the URIResolver interface, or null.
   */
  public abstract URIResolver getURIResolver();

  /**
   * Set the output properties for the transformation.  These
   * properties will override properties set in the Templates
   * with xsl:output.
   *
   * <p>If argument to this function is null, any properties
   * previously set are removed, and the value will revert to the value
   * defined in the templates object.</p>
   *
   * <p>Pass a qualified property key name as a two-part string, the namespace
   * URI enclosed in curly braces ({}), followed by the local name. If the
   * name has a null URL, the String only contain the local name. An
   * application can safely check for a non-null URI by testing to see if the
   * first character of the name is a '{' character.</p>
   * <p>For example, if a URI and local name were obtained from an element
   * defined with &lt;xyz:foo
   * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
   * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
   * Note that no prefix is used.</p>
   * An <code>IllegalArgumentException</code> is thrown  if any of the
   * argument keys are not recognized and are not namespace qualified.
   *
   * @param oformat A set of output properties that will be used to override any of the same
   * properties in affect for the transformation.
   * @throws IllegalArgumentException When keys are not recognized and are not namespace qualified.
   * @see javax.xml.transform.OutputKeys
   * @see java.util.Properties
   */
  public abstract void setOutputProperties(Properties oformat);

  /**
   * <p>Get a copy of the output properties for the transformation.</p>
   *
   * <p>The properties returned should contain properties set by the user,
   * and properties set by the stylesheet, and these properties
   * are "defaulted" by default properties specified by
   * <a href="http://www.w3.org/TR/xslt#output">section 16 of the
   * XSL Transformations (XSLT) W3C Recommendation</a>.  The properties that
   * were specifically set by the user or the stylesheet should be in the base
   * Properties list, while the XSLT default properties that were not
   * specifically set should be the default Properties list.  Thus,
   * getOutputProperties().getProperty(String key) will obtain any
   * property in that was set by {@link #setOutputProperty},
   * {@link #setOutputProperties}, in the stylesheet, <em>or</em> the default
   * properties, while
   * getOutputProperties().get(String key) will only retrieve properties
   * that were explicitly set by {@link #setOutputProperty},
   * {@link #setOutputProperties}, or in the stylesheet.</p>
   *
   * <p>Note that mutation of the Properties object returned will not
   * effect the properties that the transformer contains.</p>
   *
   * <p>If any of the argument keys are not recognized and are not
   * namespace qualified, the property will be ignored and not returned.
   * In other words the behaviour is not orthogonal with
   * {@link #setOutputProperties setOutputProperties}.</p>
   *
   * @return A copy of the set of output properties in effect for the next transformation.
   * @see javax.xml.transform.OutputKeys
   * @see java.util.Properties
   * @see <a href="http://www.w3.org/TR/xslt#output"> XSL Transformations (XSLT) Version 1.0</a>
   */
  public abstract Properties getOutputProperties();

  /**
   * Set an output property that will be in effect for the
   * transformation.
   *
   * <p>Pass a qualified property name as a two-part string, the namespace URI
   * enclosed in curly braces ({}), followed by the local name. If the
   * name has a null URL, the String only contain the local name. An
   * application can safely check for a non-null URI by testing to see if the
   * first character of the name is a '{' character.</p>
   * <p>For example, if a URI and local name were obtained from an element
   * defined with &lt;xyz:foo
   * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
   * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
   * Note that no prefix is used.</p>
   *
   * <p>The Properties object that was passed to {@link #setOutputProperties}
   * won't be effected by calling this method.</p>
   *
   * @param name A non-null String that specifies an output property name, which may be namespace
   * qualified.
   * @param value The non-null string value of the output property.
   * @throws IllegalArgumentException If the property is not supported, and is not qualified with a
   * namespace.
   * @see javax.xml.transform.OutputKeys
   */
  public abstract void setOutputProperty(String name, String value)
      throws IllegalArgumentException;

  /**
   * <p>Get an output property that is in effect for the transformer.</p>
   *
   * <p>If a property has been set using {@link #setOutputProperty},
   * that value will be returned. Otherwise, if a property is explicitly
   * specified in the stylesheet, that value will be returned. If
   * the value of the property has been defaulted, that is, if no
   * value has been set explicitly either with {@link #setOutputProperty} or
   * in the stylesheet, the result may vary depending on
   * implementation and input stylesheet.</p>
   *
   * @param name A non-null String that specifies an output property name, which may be namespace
   * qualified.
   * @return The string value of the output property, or null if no property was found.
   * @throws IllegalArgumentException If the property is not supported.
   * @see javax.xml.transform.OutputKeys
   */
  public abstract String getOutputProperty(String name)
      throws IllegalArgumentException;

  /**
   * Set the error event listener in effect for the transformation.
   *
   * @param listener The new error listener.
   * @throws IllegalArgumentException if listener is null.
   */
  public abstract void setErrorListener(ErrorListener listener)
      throws IllegalArgumentException;

  /**
   * Get the error event handler in effect for the transformation.
   * Implementations must provide a default error listener.
   *
   * @return The current error handler, which should never be null.
   */
  public abstract ErrorListener getErrorListener();
}
